## Knowledge Base » SigmaXL Toolbox

What Distribution Best Fits a Single Variable Data Set

on January 01, 2012

*I have a single
variable data set in Excel. How do I determine what distribution best fits the
data?*

**SigmaXL Version
6 includes powerful tools to deal with nonnormal data.**

Specific to the
question, we have a **Distribution Fitting** option that allows
you to do any of the following:

· **Specify a distribution or transformation:**

- Based on theory or process knowledge
- Supported Distributions: Normal,
Half-Normal, Lognormal (2 & 3 parameter), Exponential (1 & 2
parameter), Weibull (2 & 3 parameter), Beta (2 & 4 parameter),
Gamma (2 & 3 parameter), Logistic, Loglogistic (2 & 3 parameter),
Largest Extreme Value, Smallest Extreme Value
- Supported Transformations: Box-Cox
Power, Johnson Family
- Note that we use Anderson Darling (AD)
Goodness of Fit rather than Chi-Square.
**AD is a more powerful test than Chi-Square.**

· **Automatic Best Fit:**

- All of the above transformations and
distributions (that are valid for the data) are applied and SigmaXL
selects the best based on the AD p-value estimate.

· **All Distributions:**

- All valid distributions and
transformations reported with histograms, curve fit and probability plots
sorted by AD p-value

· **Process Capability Indices and Control Charts are also available.**

The SigmaXL Workbook gives more information on this topic.

Statistical
details are given in the appendix of the SigmaXL Workbook.

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